While the invention is subject to a wide range of applications, it is especially suited for use in an electrical lighting fixture and will be particularly described in that connection.
The present invention provides an improved swivel assembly which may be used for a variety of purposes. One particularly useful application of the assembly is in an electrical lighting fixture for attaching a lamp housing to a lamp support, and thereby permits adjustment of the position of the lamp housing relative to the support. For example, one specific type of electrical lighting fixture in which the present swivel assembly may be used is a pole lamp. This lamp comprises a long supporting standard, or pole, which is normally installed in an upright position between floor and ceiling of a room. A number of lamp housings may be mounted on the pole along spaced positions and attached to the pole by means of a swivel assembly.
The electrical swivel assembly used in the lighting fixture may comprise a housing having means for attachment to the lamp support and a swivel member mounted in the housing and having means for attachment to a lamp housing. The swivel assembly has a central opening extending through the swivel housing and the swivel member for receiving the electrical conductors which carry electrical current to a lamp within the lamp housing. In some of the existing electrical swivel assemblies of this type, the swivel member has only one degree of adjustment relative to the swivel housing, i.e. typical adjustment about an axis generally normal to the longitudinal axis of the swivel housing. Often, this type of swivel assembly cannot be used as it limits the adjustment of the lamp housing relative to the lamp support. Accordingly, an improved type of electrical swivel assembly has been devised wherein the swivel member has two degrees of adjustment relative to the swivel housing, i.e., pivotal adjustment about an axis normal to the longitudinal axis of the swivel housing and rotational adjustment about the latter axis. This improved swivel assembly requires to have the angle of rotational adjustment of the swivel member to be limited in order to prevent excessive twisting of the electrical conductors which extend through the swivel assembly when it is installed on a lighting fixture. In the past, the means for limiting the angle of rotational adjustment was rather complicated and therefore expensive to manufacture and assemble. Also, the means used to limit the rotational adjustment were often not very sturdy. In addition, the previous electrical swivel assemblies often had the pivotal adjustment of the swivel member restricted to one plane. In other words, the swivel member did not have the capability of universal swivel movement relative to the swivel housing. Further, when a heavy load, such as a heavy lamp was attached to the swivel, the swivel often could not hold the lamp at the exact desired position.
U.S. Pat. No. 3,312,482 to Barrett et al, discloses for example, "an improved swivel assembly wherein the adjustment of the swivel member relative to the swivel housing is limited in a unique way which affords the swivel member with a greater degree of freedom of adjustment than are the swivel members of the existing swivel assemblies." This reference partially overcomes the prior deficiencies but requires a relatively complicated and therefore expensive structure to overcome these problems.
U.S. Pat. No. 3,186,736 to Warshawsky discloses, for example "is directed to improve swivel joint fittings for lighting fixtures through which electric wire extends". This reference illustrates a swivel which may have difficulties in supporting a heavy light assembly in a desired position.
Accordingly, it is an object of the present invention to provide an improved swivel assembly which substantially obviates one or more of the limitations and disadvantages of the described prior arrangement.
Another object of the present invention is to provide a swivel assembly which is relatively simple in construction, and economical to manufacture.